Tubing plug

ABSTRACT

A plug suitable for use in a tubing string which incorporates an elongate body formed of a slidable inner mandrel which moves a spacer ring mounted on the exterior, the spacer ring expanding a resilient pack-off element adjacent a fixed external mandrel. The apparatus is set by upward flow in the tubing string wherein upward flow forces the inner mandrel upward. A check valve arrangement is attached to the lower end of the inner mandrel. A lateral relief valve is included so that a release tool can reduce the pressure differential acting across the plug. An alternative embodiment of the plug is disclosed which includes a spring arranged between the inner and outer mandrels which spring enables the mandrels to set the plug without the necessity of downhole pressure which forces the inner mandrel upwardly in the first embodiment.

United States Patent Dutrene Feb. 25, 1975 [54] TUBING PLUG 3,433,3033/1969 Clark, Jr. et al. 166/196 [76] Inventor: Alex Dufrene, P.O. Box194, Des Primary Examiner james A pp Allemands, La. 70030 Attorney,Agent, or Fzrm-Donald Gunn [22] Filed: Sept. 10, 1973 Y Y 21 Appl. No.:396,091 1 1 ABSTRACT A plug suitable for use in a tubing string whichincor- Apphcatmn Data porates an elongate body formed of a slidableinner [63] Continuation-m-part of Ser. No. 308,327, Nov.'2l, mandrelwhich moves-a Spacer ring mounted on the 1972 exterior, the spacer ringexpanding a resilient pack-off 7 element adjacent a fixed externalmandrel. The appalfi] l66lllg8z8iblggflgg rams is Set byyupward flowjnthe tubing String wherein 196 202 upward flow forces the inner mandrelupward. A 1 0 21/7/116 2 check valve arrangement is attached to thelower end of the inner mandrel. A lateral relief valve is included 56 Rf C} d so that a release tool can reduce the pressure differen- 1 eerences l e I tial acting across the plug. An alternative embodimentUNlTED STATES PATENTS of the plug is disclosed which includes a springarl,145,l55 7/1915 Mack 166/196 ranged-between the inner and outermandrels which 1,972,791 9/1934 Qtis l66/133 spring enables the mandrelsto set the plug without the g necessity of d'ownhole pressure whichforces the inner assmger..... 3,215,208 11/1965 Tamplen 166/196 mandrelupwardly m the first embod'mem' 3,283,823 11/1966 Warrington 166/196 8Claims, 8 Drawing Figures BACKGROUND OF THE' INVENTION In production ofoil wells, it is sometimes necessary to place a plug in a tubing string.Plugging a tubing string is measurably different from placing a plug inan open bore or in a drill pipe. Normally, a tubing string is quitenarrow in comparison with an open hole or cased hole, and it isgenerally undesirable to set metal slips in a tubing string in view ofthe potential for damaging the sidewall of the tubing.

Leakage-past a plug is a critical factor. Often, a plug is placed in atubing string to test for leaks at otherplaces in the productionequipment. Leakage past the plug in the tubing string is extremelyundesirable because it will cloud the results of the test. Accordingly,

the present invention has been provided as a means of plugging a tubingstring with a minimum of leakage. The device is believed successfulwherein previous attempts have failed.

SUMMARY OF THE PRESENT INVENTION The present invention is summarized asincorporating a plug which is particularly adapted to be used in atubing string. The plug incorporates a pair of telescoped mandrels. Theouter mandrel-is adapted to be FIG. 5 is a view similar to FIG. 4Ashowing the alternative embodiment of the present inventionactuated andplugging the tubing string; and 1 FIG. 6 is a view similar to FIG. 3showing a release 5 tool inserted into the plug of the present inventionto connected by means of a crossover with a tubing lock to be run in atubing string. The outer mandrel abuts at its lower end a rubber packingelement. The packing element is in the form of a resilient cup which isfitted about an inner mandrel. The inner mandrel has a down or relaxedposition and an up position which carries a 'spacerring against thepack-off element to expand the cup. The lower mandrel is movable inresponse to bottomhole. pressure. The lower mandrel incorporates a valvecage which'surrounds a check valve mechanism.

The check valve mechanism permits pumping down BRIEF DESCRIPTION OF THEDRAWINGS FIGS. lAand 1B jointly show the full length of the tubing plugof the present invention in sectional view, thereby illustrating theinternal details of construction;

FIG. 2 is a view similar to FIG. 1A showing the tool of the presentinvention actuated and plugging the tubing string;

FIG. 3 is a view similar to FIG. 2 showing a release t'ool inserted intothe plug of the present invention to release it from the plug positionof FIG. 2;

FIG. 4A and 4B jointly show the full length of an alternative embodimentof the tubing plug in sectional view, thereby illustrating internaldetails of construction;

release it from the plug position of FIG. 5.

In'the drawings, the numeral 10 generally indicates the plug of thepresentinvention. It is adapted to be run in on a connector 12, and isadapted to be placed in a tubing string. The tool of the presentinvention is preferably run in below a tubing joint or pre-set nipple,one suitable version thereof being manufactured by Baker Oil Tools andbearing the model designation TS2"tub-. ing joint lock. Camco alsomanufactures suitable lock or stop equipment for use with the presentinvention. The lock or stop apparatus is located above the tool of thepresent invention which constitutes the bottom most installation of theapparatus used for running it into the tubing string.

The plug 10 of the present invention incorporates a crossover 14 whichis a double ended, threaded adapter for interconnection withthe'apparatus located thereabove. The lower portion of the crossover I4threadedly connects at 16 to the outer mandrel 18. The outer mandrel isthreaded internally as illustrated in FIG. IA. The outer mandrel ishollow through its center and includes an upwardly facing shoulder 20which assists in assembly of the tool. The outer mandrel l8 surrounds aninner. mandrel 22 which has an enlargement at 24 which cannot pass belowthe shoulder 20. This is more amply illustrated in FIG. 1A. Theenlargement 24 fits within the outer mandrel 18 in a manner to permitupward movement of the inner mandrel 22.

The outer mandrel 18 fits snuggly about the inner mandrel .22 anda sealmeans 26 is found at twolocations below the shoulder 20. In thepreferred embodiment, the seal means preferably incorporates an O-ringof resilient material placed in an encircling groove.

The inner mandrel 22 has a lower portion which sup ports a sliding,resilient cup or pack-off element 28. The cup member 28 is tubular andis telescoped over the mandrel. The rubber or resilient cup abutsagainst the outer mandrel 18. The outer mandrel 18 overlaps slightly atan overhanging shoulder 30 which tends to capture the cup member 28.The: cup 28 is abutted at its lower end by a spacer ring 32 which isheld in position on the inner mandrel22 at a small shoulder 34. Theshoulder 34 faces downwardly and secures the thimble 32 in position. Thespacer ring 32 incorporates the relative upward force acting on thelower side of the-resilient pack-off element 281 as will be describedhereinafter.

The inner mandrel 22 is shown in FIG. 1B terminating at athreaded'connection 46 into an equalizing sub 48. The sub 48 has acentral axial passage 50 which narrows at a shoulder 52 in the lowerportions of the sub 48. The central passage is smaller below theshoulder 52. The smaller passage is indicated by the numeral 54. Thepassage 54 extends downwardly to a valve seat 56. The valve seat 56abuts against a valve element 60 which is carried on an elongate bodyand which has a contoured truncated conical face 62 at its upper edge.The conical face 62 is interrupted to receive a seal washer 64. Thevalve body 60 has an appropriate number of seal members, preferablyresilient O-rings received in annular grooves, as indicated at 66.

The sub 48 includes the valve seat 56 which flares outwardly to acountersunk, enlarged passage which snuggly receives the upper end ofthe valve element 60. The'lower portions of the sub 48 include athreaded, interconnection 70 which enables joinder of a lower valve cage72 to the sub 48.

The valve cage 72 is a generally hollow, cylindrical body which isdrilled at several locations such as 74 and 76 to receive fluid flowinto an internal passage 78. The passage 78 incorporates an upwardlyfacing shoulder 80 and a resilient coil spring 82 is positioned aboutthe valve element 60 and bears on the shoulder 80 and the valve element60 to force the element upwardly into contact with the valve seat 56. Aswill be observed, fluid flow is permitted downwardly through the passage50 and past the check valve arrangement shown inFIG. 1B. Fluid flowexists from the valve cage 72 through the passages 74 and 76. The fluidflow in that direction must overcome the bias of the spring 82. However,flow in the opposite direction is prevented by the check valvearrangement illustrated.

The sub 48 incorporates a pressure relief valve which protrudes into thepassage 50. It incorporates a stem 82 which has a semicircularenlargement 84 protruding into the passage 50. A hollow threaded nut 86surrounds a compressed coil spring 88. The spring 88 forces the shaft 82to the left. The shaft supports a seal member 90 which is sealed againsta tapered circular shoulder 92. A flow path from the exterior is createdwhen the shaft or stem 82 is forced to the right, opening the sealmember 90 from the tapered shoulder and permitting the flow of pressurefluid through the hollow nut 88 and externally through a small port 94.

The numeral 96 in FIG. 1A identifies facing ports in the outer sub 18.The ports 96 preferably align to enable insertion of a tool for purposesof assembly. The ports 96 do not function in the operation of the wellplug.

Referring to FIG. 2, the anchor tool relatively forces the outer mandrell8 downwardly. The inner mandrel 22 moves upwardly carrying with it thekeeper nut 44 which forces the ring 32 upwardly and against theresilient member 28. The resilient member 28 expands and comes intosealing contact with the tubing string. The upward range of travel islimited by contact of the upper end of the inner mandrel 22 against thelower end of the crossover sub 14. At this juncture, the tool had beenexpanded and has closed off the tubing string. It is maintained in thisposition by pressure from below in the tubing string. The running intool can then be retrieved and removed.

Attention is directed to FIG. 3 where a retrievable tool 98 is shown. Itincorporates a body which fits fairly sungly within the passage 50 inthe sub 48. It also carries an elongate probe which fits through thenarrow passage 54 and contacts against the shoulder 52. The

retrieval tool 98 is preferably sized in dimension so that the bypassvalve mechanism is first operated. The enlargement 84 is forced to theright as illustrated in FIG. 3, clearing the check valve mechanism andpermitting pressure to flow from the exterior to the interior of thetool. The small port 94 assures a relatively slow flow so that there isno sudden surge. At this juncture, the running in too] can be retrievedalong with the plug inasmuch as the resilient member 28 has beendisengaged with the tubing string wall. The inner mandrel 22 has beenforced downwardly by the retrieval tool 98 and the resilient cup 28 hasrelaxed. This permits upward retrieval of the tool for subsequent use.

Attention is next directed to FIGS. 4A and 4B which disclose analternative embodiment of the present invention. The embodiment differsslightly as will be described but has many similar parts. Accordingly,the reference numerals found on FIGS. 1A and 18 have been transferred toFIGS. 4A and 4B increased by 100 so that the foregoing description forthe embodiment 10 can be adapted for the embodiment 100 with theexceptions noted below. The outer mandrel is identified as 118 while theinner mandrel is 122. The mandrel 122 has a downwardly facing shoulder102 on the exterior. The shoulder faces and is spaced from an upwardlyfacing shoulder 106 in the outer mandrel 118. The shoulders are spacedapart in the unsetposition and a spring 104 is received between them. Anannular space is defined between the two mandrels and is limited at thetop and bottom by the two shoulders to receive the spring I04.Preferably, the spring has several turns and is compressed in the viewillustrated in FIG. 4A.

The spring 104 is in its compressed state in FIG. 4A. FIG. 5 shows it inan extended position after expansion. Expansion of the spring occurs atthe time the tool is installed. Thus, FIG. 4A discloses thepacking-element 128 in the relaxed condition. The packer 128 is expandedwhen the inner mandrel moves upwardly relative to the outer mandrel.This upward movement is achieved in the embodiment 10 through the use ofdownhole pressure. In the embodiment 110, the relative movement of thetwo mandrels can be initiated by release of theinner mandrel to moveupwardly relative to the outer mandrel. Thus, the packer 128 can beexpanded without downhole pressure differential acting across the tool.

The inner mandrel 124 is held in the down position prior to installationby a tool 108 shown in FIG. 4A which is inserted against the top portionof the inner mandrel 122. In other words, the mandrel 122 is held in thedown position in FIG. 4A by the inserted tool 108. When the toolis.removed, the spring 104 is permitted to expand. This drives the innermandrel upwardly in the same manner as described before. When it movesupwardly, the packing element 128 is expanded into the plugged position.When it plugs, the accummulation of downhole pressure thereafter aidsand assists in maintaining the inner mandrel in the elevated position,keeping the tool set in the same manner as described with respect to theembodiment 10.

The alternative embodiment is released in the same manner as that shownin FIG. 3. A release tool 198 is inserted and the inner mandrel 128 canbe forced downwardly by downward manipulation of the tool 198. It shouldbe kept in mind that the tool 198 releases pressure through the lateralport in the manner described with respect to embodiment l0 and can alsobe used to force the inner mandrel 12 2 downwardly, thereby relievingexpansion of the packing element 128. Thus downward movement compressesthe spring 104, restoringit to the state illustrated in FIG. 4A.

I Except in the regards noted herein, the operation of the embodiment110 is similar to that of the embodiment l0.

The foregoing constitutes the description of pre-' ferred embodiment aswell as alternative embodiments of the present invention, the scope ofwhich is determined by the claims which are appended hereto.

I claim: 1. A plug for use in a tubing string comprising: a hollow,elongate outer mandrel; an elongate, hollow inner mandrel telescopedwithin said outer mandrel and movable relatively upwardly and downwardlythereof and having a portion extending therebelow; an annular, radiallyoutwardly expandable member received in telescoping arrangement aboutthe lower portion of said inner mandrel and abutting the lower end ofsaid outer mandrel; means received on the exterior of the lower portionof said inner mandrel below said expandable member for abutting thelower portions thereof and capturing said expandable member for radialexpansion on upward movement of said inner mandrel; means forselectively closing the lower portion of said outer mandrel against theupward flow of fluid through the tubing string; an axial passagecommunicating through said inner mandrel; a valve cage of elongateexternal configuration connected with said passage; check valve means insaid valve cage including a valve element and a cooperative valve seat;opening means in said valve cage to the exterior from said passage meanswith said valve means interposed therebetween to limit flow in onedirection through said passage means; and, acompressible spring operablebetween said outer and inner mandrels selectively moving them relativelyto expand said expandable member. 2. A plug for use in a tubing stringcomprising: a hollow, elongate outer mandrel; an elongate, hollow innermandrel telescoped within said outer mandrel and movable relativelyupwardly and downwardly thereof and having a portion extendingtherebelow; an annular, radially outwardly expandable member received intelescoping arrangement about the lower portion of said inner mandreland abutting the lower end of said outer mandrel;

means received on the exterior of the lower portion of said innermandrel below said expandable member for abutting the lower portionsthereof and capturing said expandable member for radial expansion onupward movement of said inner mandrel;

means for selectively closing the lower portion of said outer mandrelagainst the upward flow of fluid through the tubing string;

an internal shoulder in a passage in said inner mandrel and adapted toreceive therein an elongate releasing tool having an extending portionand adapted to land on said shoulder;

a laterally directed choke controlled valve means blocking flow from theexterior of said inner mandrel, said valve means being controlled bysuch a releasing tool and being located below said shoultively to expandsaid expandable member.

3. The apparatus of claim 2 wherein said valve means includes a stempositioned at a point where such a releasing tool moves said stem;

' a valve seat adjacent to said stem;

a cooperative valve element carried on said stem;

spring means urging said stem toward a closed position; and,

passage means having a restriction therein communicating from said valveseat to a point exterior of said inner mandrel.

4. The apparatus of claim 3 including a second check valve meanscommunicating from the exterior of said inner mandrel constructed andarranged to be released by the same releasing tool after release of saidfirst check valve means.

5. A plug for use in a tubing string comprising:

a hollow, elongate outer mandrel;

an elongate, hollow inner mandrel telesecoped within said outer mandreland movable relatively upwardly and downwardly thereof and having aportion extending therebelow; I

an annular, radially outwardly expandable member received in telescopingarrangement about the lower portion of said inner mandrel and abuttingthe lower end of said outer mandrel; i

means received on the exterior of the lower portion of said innermandrel below said expandable member for abutting the lower portionsthereof and capturing said expandable member for radial expansion onupward movement of said inner mandrel;

means for selectively closing the lower portion of said outer mandrelagainst the upward flow of fluid through the tubing string;-

an overlapping peripheral shoulder on said outer mandrel overhangingsaid expandable means to an extent sufficient to lock same on expansion;

a ring belowsaid expandable means, said ring surrounding said innermandrel and further positioned adjacent to a shoulder means thereon;

means for limiting the relative range of movement of said inner mandrelto said outer mandrel on expansion of said expandable means;

means for limiting fluid flow through said plug to the downwarddirection in the tubing string; and,

a compressible spring operable between said outer and innermandrelsselectively moving them relatively to expand said expandable member.

6. The apparatus of claim 5 wherein said expandable means includes anencircling resilient sleeve-shaped packer element, and vsaid ring iscontacted along its lower portions by an encircling swab cup, said swabcup including an inwardly directed lip adjacent to said thimble; and anencircling jam nut is positioned about said inner mandrel and forcessaid swab cup upwardly on relative upward motion of said inner mandrel.

7. The apparatus of claim 6 wherein said jam nut has a tubular extendingupper portion bearing on the nether side of said swab cup.

8. The apparatus of claim 7 wherein a tubular valve cage joins to saidinner mandrel below said keeper nut.

1. A plug for use in a tubing string comprising: a hollow, elongateouter mandrel; an elongate, hollow inner mandrel telescoped within saidouter mandrel and movable relatively upwardly and downwardly thereof andhaving a portion extending therebelow; an annular, radially outwardlyexpandable member received in telescoping arrangement about the lowerportion of said inner mandrel and abutting the lower end of said outermandrel; means received on the exterior of the lower portion of saidinner mandrel below said expandable member for abutting the lowerportions thereof and capturing said expandable member for radialexpansion on upward movement of said inner mandrel; means forselectively closing the lower portion of said outer mandrel against theupward flow of fluid through the tubing string; an axial passagecommunicating through said inner mandrel; a valve cage of elongateexternal configuration connected with said passage; check valve means insaid valve cage including a valve element and a cooperative valve seat;opening means in said valve cage to the exterior from said passage meanswith said valve means interposed therebetween to limit flow in onedirection through said passage means; and, a compressible springoperable between said outer and inner mandrels selectively moving themrelatively to expand said expandable member.
 2. A plug for use in atubing string comprising: a hollow, elongate outer mandrel; an elongate,hollow inner mandrel telescoped within said outer mandrel and movablerelatively upwardly and downwardly thereof and having a portionextending therebelow; an annular, radially outwardly expandable memberreceived in telescoping arrangement about the lower portion of saidinner mandrel and abutting the lower end of said outer mandrel; meansreceived on the exterior of the lower portion of said inner mandrelbelow said expandable member for abutting the lower portions thereof andcapturing said expandable member for radial expansion on upward movementof said inner mandrel; means for selectively closing the lower portionof said outer mandrel against the upward flow of fluid through thetubing string; an internal shoulder in a passage in said inner mandreland adapted to receive therein an elongate releasing tool having anextending portion and adapted to land on said shoulder; a laterallydirected choke controlled valve means blocking flow from the exterior ofsaid inner mandrel, said valve means being controlled by such areleasing tool and being located below said shoulder; and, acompressible spring operable between said outer and inner mandrelsselectively moving them relatively to expand said expandable member. 3.The apparatus of claim 2 wherein said valve means includes a stempositioned at a point where such a releasing tool moves said stem; avalve seat adjacent to said stem; a cooperative valve element carried onsaid stem; spring means urging said stem toward a closed position; and,passage means having a restriction therein communicating from said valveseat to a point exterior of said inner mandrel.
 4. The apparatus ofclaim 3 including a second check valve means communicating from theexterior of said inner mandrel constructed and arranged to be releasedby the same releasing tool after release of said first check valvemeans.
 5. A plug for use in a tubing string comprising: a hollow,elongate outer mandrel; an elongate, hollow inner mandrel telesecopedwithin said outer mandrel and movable relatively upwardly and downwardlythereof and having a portion extending therebelow; an annular, radiallyoutwardly expandable member received in telescoping arrangement aboutthe lower portion of said inner mandrel and abutting the lower end ofsaid outer mandrel; means received on the exterior of the lower portionof said inner mandrel below said expandable member for abutting thelower portions thereof and capturing said expandable member for radialexpansion on upward movement of said inner mandrel; means forselectively closing the lower portion of said outer mandrel against theupward flow of fluid through the tubing string; an overlappingperipheral shoulder on said outer mandrel overhanging said expandablemeans to an extent sufficient to lock same on expansion; a ring belowsaid expandable means, said ring surrounding said inner mandrel andfurther positioned adjacent to a shoulder means thereon; means forlimiting the relative range of movement of said inner mandrel to saidouter mandrel on expansion of said expandable means; means for limitingfluid flow through said plug to the downward direction in the tubingstring; and, a compressible spring operable between said outer and innermandrels selectively moving them relatively to expand said expandablemember.
 6. The apparatus of claim 5 wherein said expandable meansincludes an encircling resilient sleeve-shaped packer element, and saidring is contacted along its lower portions by an encircling swab cup,said swab cup including an inwardly directed lip adjacent to saidthimble; and an encircling jam nut is positioned about said innermandrel and forces said swab cup upwardly on relative upward motion ofsaid inner mandrel.
 7. The apparatus of claim 6 wherein said jam nut hasa tubular extending upper portion bearing on the nether side of saidswab cup.
 8. The apparatus of claim 7 wherein a tubular valve cage joinsto said inner mandrel below said keeper nut.